Plate type heat exchanger



April 20, 1954 N. R. G. EKWALL PLATE TYPE HEAT EXCHANGER v .e I a 4 Patented Apr. 20, 1954 UNITED STATES ATENT OFFICE PLATE TYPE HEAT EXCHANGER Nils Richard Gosta Ekwall, Nykoping, Sweden Application March 21, 1950, Serial No. 150,855

Claims priority, application Sweden March 26, 1949 8 Claims. 257-245) My present invention relates to plate type heat exchangers, particularly for use in pasteurizing apparatus, wherein the plates, in combination with packing means about the margins, define the perimeters of spaces communicating alternately with inlets and outlets for the media subjected to exchange of heat in the apparatus, one of said media for example being milk or cream. Such plates are commonly provided with ridgelike projections within the spaces, said projections extending transversely of the direction of flow of the media in the spaces and terminating short of the side margins of the spaces. The projections have as their object an increase in the heat transferring surface and the improvement of the factor of heat transmission between the sheet material and the respective media by imparting to the latter a sinuous or undulating turbulent flow. This kind of flow, however, cannot be maintained along the marginal spaces between the ends of the projections and the adjacent packing means, with the usual construction, there being a relatively straight path at each end of the transverse projections, extending along the side margins of the spaces in the direction of flow of the media.

One object of my invention is to shape the plates so as to avoid narrow pockets or intervening spaces, wherein the milk might be subjected to burning, without giving the plates an undesirable configuration in other respects.

A further object of my invention is to shape said plates so as to subject the fluid therein, especially milk being pasteurized, to substantially the same treatment as between the projections, the space between the plates being thus utilized in the most efficient manner for the purpose in view.

Further objects and advantages of the invention will be apparent from the following description considered in connection with the accompanying drawing, which forms a part of this specification, and of which:

Fig. 1 is a plan view of a plate and Fig. 2 a section on the line IIII of Fig. 1.

The plate apparatus is built from plates [0 disposed in parallel adjacent to one another, so that spaces are formed between them for flow of the media subjected to exchange of heat in the apparatus. In pasteurizing apparatus one of such media consists of milk or cream. Said spaces are defined laterally by packing means comprising gaskets I! in the form of strips of rubber or a similar material, and inserted into the endless channels I 4 formed in the plates and defining the perimeters of the spaces when the plates are 2 assembled. The plates, which are of substantially rectangular shape, are provided with openings in their corners for the respective media, the channels and gaskets [2 extending outside of diagonally opposed openings in the plates. Thus the packing 12 extends outside the two apertures IE and I 8 in Fig. 1, which thus form the inlet and the outlet respectively for one of the spaces, through which one of the fluids flows. The two other openings 20 and 22 are blocked off with the aid of round packing rings 24 from the space enclosed by this packing. In the next space conditions are reversed, in that the packing therein encloses the openings 28 and 22, which then form the inlet and outlet respectively for the adjacent space through which the other fiuid flows, while the openings 16 and I8 are blocked off from the space by means of round packing rings (not shown). In this manner one fluid flows through alternate spaces, while the other fluid flows through the intervening spaces, preferably in counter-current direction. The fluids flow over the major portions of the plates which are pro-' vided with projections 26 extending transversely of the direction of flow, these portions of the spaces producing a wave-like or sinuous flow oi the fluids in a plane normal to the planes of the plates, this feature having a favorable effect on the operation of the apparatus, as stated.

Preferably all of the transverse projections are of the same length. but are alternately displaced in the same plate relative to one another longitudinally so that their ends are staggered. Furthermore, the channel It and the packing strip I2 are wave-shaped or sinuous opposite that portion of the plate provided with transverse projections, as is indicated at 28 in Fig. 1, by being curved inwardly toward the ends 01 the alternate projections furthest from the margin. In this way a passage 38 is formed between the inner wall of the channel it and the sloping or bevelled ends 32 of the projection which preferably commence a short distance therefrom, said passage being wave-shaped or sinuous in the plane of the plate, in contrast with the space between the transverse projections, which is wave-shaped or sinuous in a plane normal thereto and extending in the direction of the length of the plate. Furthermore, the passage preferably has a cross section, which is constant, approximately at least, between the projections and the packing strip in the direction of flow of the fluid. Consequently the fluid flowing between two plates will have an undulatory or sinuous flow along the portion 28 of the packing strip in the plane of the plate, whereby turbulent flow is imparted to the fluid, while.

burning of a fluid such as milk is at the same time effectively prevented. The cross section of the channel may be adapted in a favourable manner with respect to the resistance to flow, and pockets wherein the fiuid would remain more or less stationary are avoided entirely.

While one more or less specific embodiment of the invention has been shown, it is to be understood that this is for purpose of illustration only, and the invention is not to be limited thereby,

. its scope being determined by the appended claims.

What I claim is:

1. A plate type heat exchanger comprising a plurality of heat exchange plates, means between each two adjacent plates defining the perimeter of a space therebetween for flow of fluid, means providing inlets and outlets for each of ,said spaces, projections extending transversely across said plates between said inlets and said outlets to provide spaces of sinuous form in a plane normal to the planes of the plates, said projections terminating short of the perimeters of said spaces and the means defining the portions of the perimeters adjacent to the ends of the projections being shaped to provide passages between the ends of said projections and said means of sinuous form in the planes of the plates.

2. Apparatus as defined in claim 1 in which the means defining the perimeters of the spaces comprises endless channels formed in the plates and packing strips in said channels, the portions of said channels adjacent to the ends of said transverse projections being of sinuous form.

3. Apparatus as defined in claim 2 in which the transverse projections and the endless channels of each plate extend from the same side of the plane of the plate. 7 v

4. Apparatus as defined in claim 2 in which the ends of the transverse projections are staggered and confront the adjacent means forming the sinuous portions of. the perimeters of the spaces to provide, sinuous passages of substantially constant flow area.

5. Apparatus as defined in claim 4 in which the ends of said transverse projections are bevelled.

6. For use in plate type heat exchangers, a plate having an endless channel formed therein defining the perimeter of a space and adapted to receive a packing member, opposed portions of said channel being of sinuous form, a series of parallel projections-formed in the plate and extending transversely thereof between said portions, said projections terminating short of said portions to'provide sinuous marginal passages adjacent to said portions of sinuous form, and an opening in the plate of each side of said series of projections, said openings being within said perimeter.

7. For use in plate type heat exchangers, a plate having an endless channel formed therein defining the perimeter of a space and adapted to receive a packin member, said channel having substantially parallel side portions of sinuous form'and substantially parallel oblique end portions, a series of projections extending transversely between said sinuous side portions and terminating short thereof, and openings in the diagonally opposite and most remote corners of said space adjacent to said oblique end portions of said channel.

8. A plate as defined in claim 7 in which the ends of said transverse projections are staggered to provide marginal sinuous passages along the sides of said space.

References Cited in the file of this patent UNITED STATES; PATENTS Number Name Date 2,039,216 Feldmeier Apr. 18, 1936 2,193,405 Goodman Mar. 12, 1940 2,550,339 Ehrman Apr. 24; 1951 FOREIGN PATENTS Number Country Date 57,996 Denmark Sept. 16, 1940 

